As for traditional treatment modes prior to testing of a liquid sample to be tested, it generally involves steps of sampling, sample preparation, weighing, liquid-liquid partition extraction, solid phase extraction purification, sample filtration, sample transferring and the like. These steps currently are operated stepwise and independently: for example, after completion of the steps of sampling, sample preparation, and weighing of the liquid sample to be tested, a separate appliance and a step are required for performing liquid-liquid partition extraction, then another appliance or apparatus is used for performing the step of solid phase extraction purification, and then a further apparatus or appliance is required to be used for performing the step of sample filtration, and finally the same applies to sample transferring.
At present, the liquid-liquid partition extraction requires a special glass bottle for liquid-liquid partition, so as to oscillate water and a solvent immiscible with water, and make the same stand and layered, and then release a lower layer via a valve, hereby completing the partition process; and it is also reported that diatomite is used to perform the liquid-liquid partition. Both methods mentioned above have the disadvantage that both require to use an individual appliance, cannot be compatible with and performed simultaneously with other steps, need to consume a massive amount of organic solvent, and generally also need a subsequent step of concentration under a reduced pressure for completion.
As for the step of solid phase extraction, a purification step is most commonly used at present. The current solid phase extraction step comprises filling a tube in the form of an injector with a solid phase extractant, and using a vacuum pump from below for forming a vacuum state such that the liquid carries the sample to pass through the solid phase extractant, hereby completing the solid phase extraction process. The completion of this step requires the configuration of a special vacuum pump and a chamber device, and cannot be compatible with other steps to be performed together. Alternatively, without using the tube in the form of an injector, a solid phase extractant is directly added to the liquid sample to be tested, for the purpose of absorbing impurities, but it has the disadvantage that extraction effect is undesirable, and that after completion of the extraction step, a filtrating or centrifuging step is inevitably required for separating the solid phase extractant from the purified sample.
Current step of sample filtration comprises transferring the liquid of the sample to be tested using a special appliance into an injector or a tube having a function of the same type, and pushing and compressing the sample within the injector using a piston, such that the sample passes through a filter membrane mounted at the bottom of the injector, hereby achieving the purpose of filtration. Finally, the filtrated sample is transferred into a corresponding glass bottle.
All the current pretreatment steps (liquid-liquid extraction, solid phase extraction purification, sample filtration, and sample transferring) of a liquid sample to be tested are performed separately, wherein the steps are tedious, and the solvent might be easily contaminated during the processes of filtration, purification and transferring, leading to the problem of inaccurate test results; moreover, multiple steps require multiple specialized appliances to be used and a greater amount of organic solvent to be consumed, influencing the stability and accuracy of the test results, and resulting in greater emission of harmful substances.